Vasquez Rocks
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Vasquez Rocks clear sky chart from 2005-11-05 to 2017-09-17.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
71%
15792
35%
46820
29%
15743
77%
15743
55%
21987

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
53%
720
29%
2473
25%
716
64%
716
38%
1218
January16th to endNight
50%
768
34%
2385
24%
768
63%
768
38%
1241
February1st to 15thNight
58%
700
33%
2107
27%
699
68%
699
44%
1094
February16th to endNight
57%
632
30%
1895
27%
632
65%
632
38%
1055
March1st to 15thNight
58%
720
28%
2160
24%
720
67%
720
47%
1079
March16th to endNight
68%
768
31%
1998
22%
768
73%
768
51%
1069
April1st to 15thNight
61%
719
31%
1799
18%
719
67%
719
52%
989
April16th to endNight
66%
720
33%
1800
17%
720
71%
720
64%
893
May1st to 15thNight
72%
620
32%
1700
21%
620
74%
620
60%
812
May16th to endNight
71%
561
34%
1685
26%
561
74%
561
66%
711
June1st to 15thNight
82%
429
35%
1509
33%
429
87%
429
69%
542
June16th to endNight
96%
360
42%
1440
52%
360
97%
360
80%
419
July1st to 15thNight
92%
340
36%
1360
42%
340
92%
340
68%
444
July16th to endNight
90%
598
35%
1620
29%
558
90%
558
65%
730
August1st to 15thNight
92%
717
38%
1790
25%
713
92%
713
82%
797
August16th to endNight
95%
764
45%
1910
31%
764
95%
764
82%
853
September1st to 15thNight
91%
720
42%
1821
34%
720
91%
720
78%
826
September16th to endNight
89%
664
46%
1837
43%
664
93%
664
82%
746
October1st to 15thNight
77%
660
38%
1842
35%
660
82%
660
60%
880
October16th to endNight
72%
704
42%
2133
40%
704
79%
704
57%
968
November1st to 15thNight
69%
700
36%
2275
33%
700
79%
700
56%
979
November16th to endNight
66%
720
37%
2340
35%
720
75%
720
51%
1071
December1st to 15thNight
57%
720
34%
2340
27%
720
68%
720
39%
1197
December16th to endNight
51%
768
31%
2601
25%
768
63%
768
33%
1374

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
3212212235%71%
47936
Night
3312212235%70%
47017
TransparencyDay
16%26%15%28%29%
47628
Night
17%27%15%27%29%
46826
SeeingDay
411%32%34%12%4
5919
Night
3415%34%33%8%
15799

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
6%323323235%61%
1462
16th to endDay
9%5%25%213335%57%
1836
February1st to 15thDay
5%423313246%61%
1751
16th to endDay
7%6%145%2334455%
1579
March1st to 15thDay
421332345%7%59%
1800
16th to endDay
342432445%8%57%
2221
April1st to 15thDay
5%413212236%65%
2149
16th to endDay
1212212246%71%
2160
May1st to 15thDay
1322213235%71%
2250
16th to endDay
2212112235%73%
2429
June1st to 15thDay
122211225%77%
2447
16th to endDay
11111288%
2520
July1st to 15thDay
111221222379%
2520
16th to endDay
2111111245%76%
2429
August1st to 15thDay
11112384%
2160
16th to endDay
11111385%
2292
September1st to 15thDay
11111211383%
2139
16th to endDay
1112112283%
1828
October1st to 15thDay
312212345%71%
1785
16th to endDay
121221323374%
1738
November1st to 15thDay
221222233471%
1584
16th to endDay
3323212347%63%
1620
December1st to 15thDay
341322445%8%57%
1620
16th to endDay
9%413423336%56%
1617
January1st to 15thNight
6%423213446%59%
2473
16th to endNight
7%5%24322346%58%
2385
February1st to 15thNight
45%23312345%61%
2101
16th to endNight
6%6%25%413445%56%
1895
March1st to 15thNight
342321445%7%60%
2160
16th to endNight
331232345%7%62%
1998
April1st to 15thNight
4423212235%66%
1799
16th to endNight
2212211245%72%
1800
May1st to 15thNight
312322246%70%
1700
16th to endNight
1212112225%76%
1684
June1st to 15thNight
1112136%79%
1509
16th to endNight
111289%
1440
July1st to 15thNight
1221222380%
1440
16th to endNight
221213235%73%
1734
August1st to 15thNight
1111112384%
1800
16th to endNight
11112285%
1910
September1st to 15thNight
1111112482%
1821
16th to endNight
111122385%
1837
October1st to 15thNight
131221333473%
1842
16th to endNight
231221212474%
2133
November1st to 15thNight
231221223472%
2275
16th to endNight
2312213337%65%
2340
December1st to 15thNight
5%424324247%59%
2340
16th to endNight
6%5%23323336%57%
2601

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
25%26%14%28%21%
1462
16th to endDay
29%27%17%18%23%
1836
February1st to 15thDay
24%25%18%26%22%
1751
16th to endDay
31%27%16%30%10%
1579
March1st to 15thDay
21%410%22%21%19%
1800
16th to endDay
24%310%25%20%14%
2221
April1st to 15thDay
21%310%23%27%12%
2149
16th to endDay
13%411%21%32%16%
2160
May1st to 15thDay
15%310%19%30%21%
2250
16th to endDay
13%28%22%38%13%
2432
June1st to 15thDay
11%17%15%31%32%
2447
16th to endDay
6%126%27%56%
2520
July1st to 15thDay
11%148%21%52%
2371
16th to endDay
11%25%17%27%35%
2281
August1st to 15thDay
6%38%30%50%
2146
16th to endDay
6%138%34%46%
2292
September1st to 15thDay
7%16%9%28%46%
2139
16th to endDay
8%138%35%43%
1828
October1st to 15thDay
17%15%17%28%29%
1785
16th to endDay
15%35%11%26%38%
1738
November1st to 15thDay
18%25%15%33%25%
1584
16th to endDay
21%26%15%25%28%
1620
December1st to 15thDay
22%411%18%24%17%
1620
16th to endDay
30%48%21%21%14%
1617
January1st to 15thNight
24%36%16%26%21%
2473
16th to endNight
26%39%14%20%25%
2385
February1st to 15thNight
23%37%16%24%24%
2112
16th to endNight
29%37%17%28%12%
1895
March1st to 15thNight
21%310%19%24%19%
2160
16th to endNight
20%412%22%25%14%
1998
April1st to 15thNight
21%39%28%22%14%
1799
16th to endNight
12%310%24%30%17%
1800
May1st to 15thNight
13%48%22%31%19%
1701
16th to endNight
11%110%24%38%14%
1685
June1st to 15thNight
8%28%18%28%33%
1509
16th to endNight
5%36%26%57%
1440
July1st to 15thNight
9%138%21%55%
1360
16th to endNight
13%25%13%26%38%
1620
August1st to 15thNight
6%126%30%52%
1790
16th to endNight
6%28%33%47%
1910
September1st to 15thNight
8%148%28%48%
1821
16th to endNight
5%1210%37%42%
1837
October1st to 15thNight
16%15%14%33%29%
1842
16th to endNight
16%2211%27%39%
2133
November1st to 15thNight
16%15%14%31%30%
2275
16th to endNight
19%27%16%25%29%
2340
December1st to 15thNight
25%47%15%26%20%
2340
16th to endNight
28%49%17%23%16%
2601

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
12%26%35%21%31
90
16th to endDay
13%20%36%21%7%1
274
February1st to 15thDay
7%21%32%28%8%1
266
16th to endDay
10%23%31%25%7%
238
March1st to 15thDay
8%20%32%24%13%
270
16th to endDay
6%17%40%24%9%1
288
April1st to 15thDay
11%18%38%20%8%1
269
16th to endDay
428%37%20%6%2
270
May1st to 15thDay
316%38%29%8%3
288
16th to endDay
5%11%38%31%9%3
330
June1st to 15thDay
9%34%37%11%6%
315
16th to endDay
1429%38%15%10%
315
July1st to 15thDay
122%47%17%9%
305
16th to endDay
217%50%18%10%
327
August1st to 15thDay
129%48%12%7%
315
16th to endDay
21%51%16%10%
332
September1st to 15thDay
330%47%14%2
315
16th to endDay
16%31%41%17%1
260
October1st to 15thDay
114%40%32%10%1
255
16th to endDay
210%32%35%18%
250
November1st to 15thDay
38%23%26%26%11%
90
16th to endDay
7%13%35%34%8%
90
December1st to 15thDay
5%8%26%44%12%2
90
16th to endDay
10%19%33%28%7%
77
January1st to 15thNight
7%8%22%39%17%4
720
16th to endNight
9%8%23%35%19%2
768
February1st to 15thNight
5%423%39%21%5%
704
16th to endNight
7%6%23%36%20%4
632
March1st to 15thNight
35%26%35%22%5%
720
16th to endNight
35%18%40%27%4
768
April1st to 15thNight
46%21%38%25%3
719
16th to endNight
25%22%37%26%6%
720
May1st to 15thNight
418%40%31%4
621
16th to endNight
1418%36%33%4
563
June1st to 15thNight
111%38%43%4
429
16th to endNight
36%55%6%
360
July1st to 15thNight
120%67%10%
340
16th to endNight
2220%59%14%
598
August1st to 15thNight
1125%55%15%
717
16th to endNight
118%57%21%
764
September1st to 15thNight
1325%50%20%
720
16th to endNight
7%32%44%15%
664
October1st to 15thNight
2311%42%32%7%
660
16th to endNight
2217%33%31%12%
704
November1st to 15thNight
2218%39%29%7%
700
16th to endNight
3321%37%27%6%
720
December1st to 15thNight
6%6%20%40%22%3
720
16th to endNight
9%9%23%38%16%2
768
Page generated at 2017-09-18 05:38:20. Version ac04

Copyright 2017 A. Danko


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